1. Field of the Invention
The present invention relates to purification and recycling of germanium-69 from radioactive liquid of gallium-68, in particular to a process of development of gallium-69 in a radionuclide generator of germanium-68/gallium-68 for positron emission tomography (PET) including elution, purification and recycling. The method can be used in research and development of radionuclide generator of germanium-68/gallium-68 for PET in the radiopharmaceutical industry.
2. Description of related Art
A conventional elution and purification process for radioactive liquid includes dissolution and filtration for pre-treatment, followed by a washing operation with different concentration and volume of solutions to obtain desired radionuclide. The remaining radioactive waste solution is disposed as usual, not only ignoring the value of recycling but also increasing the pollution of environment with the radioactive waste. If the elution waste liquid containing high level of gallium-69 has not been effectively recovered for reuse in preparation of the solid target, it will result in increasing cost of production and reducing the yield of gallium-68 nuclides. Thus, there is a need for recycling of gallium-69 from the elution waste liquid for cost reduction and improving the yield of gallium-68 nuclides.
In the prior arts, US patent publication No. 2011/0214995 and Taiwan patent application No. 099 104 331, that disclosed methods of purification for obtaining no-carrier gallium-67 with condition of using 15 to 40 million electron volts (MeV) proton for irradiation of plating materials to produce desired nuclide through nuclear reaction. In chemical process, the use of ion exchange resins as an adsorbent and repetitively washing with concentrated hydrochloric acid, and finally the elution waste liquid is evaporated to obtain target nuclides. If the elution liquid of radioactive waste has not been put into recycling, it would be wasteful of resources from recycling point of view.
Gallium-68 has been drawing attention from the industry of radiopharmaceutical, because the germanium-68/gallium-68 generator system can be exploited for radiopharmaceutical related production. In the US patent publication No. US2012/0011965 and Taiwan patent application No. 099 123 148, that disclosed apparatuses and methods for production of gallium-68 isotopes in place of time consuming and costly conventional cyclotron for production of isotopes of gallium-68.
In the application of scintigraphy with PET in today's clinical trials, germanium-68/gallium-68 generator system is one of important source for the production of radiopharmaceutical, since this system has a long half-life from the mother nuclide germanium-68 to produce a short half-life daughter nuclide gallium-68. Before the process of labeling, it is found that using a specific size and concentration of hydrochloric acid in eluting the retention activity off a column may produce chlorine containing solution with no acetate ions.
After a long period of elution trials, the results revealed that use of specific volume and concentration of hydrochloric acid as condition for each column elution, the high yield of gallium-68 nuclides can be achieved. It is also found that if gallium-69 has been collected and recycled after pre-purification of a column for reproduction of solid targets, it can improve the efficiency of utilization of nuclides and also comply with the recycling notion nowadays.
In view of the above drawbacks in the conventional elution and purification process for the radioactive solution, the method of purification for recycling of gallium-69 isotopes of the present invention is made to address the issues.